Temperaturens inverkan på vinterförluster hso svenska honungsbin

Abstract

Insects, such as the honey bee, play a fundamental part in pollination of both wild plants and in agriculture and thereby a large part in the food supply for mankind. Declining numbers have been observed for both honey bees and other pollinators in different parts of the world and it is of utmost importance to understand what affects these declines. In this study, winter loss data from Swedish bee colonies has been used to investigate the relationship between loss and temperature. The data covers an average winter loss for all of Sweden from 1920–2018 and on a more detailed level from 1997–2018. Correlation analyses between annual winter loss and monthly mean temperatures have been executed and a function has been created to model winter loss based on temperature. In Götaland and Svealand, colder temperatures in October, January and February have a significant connection to higher winter loss and in Norrland the same connection applies only for February. The model overestimates the winter loss before 1997 which probably is due to the invasive mite, Varroa destructor, that came to Sweden during the 90s. Based on infected colonies the model becomes more sensitive to temperatures than it had been based on non-infested bee colonies. As climate changes so has the relationship between winter loss and the monthly mean temperature.